Certain types of mobile machinery have "working" mechanisms driven by a separate source of power rather than by, for example, the mere movement of the machine across the ground or by a machine-mounted engine. Exemplary machines of the foregoing type include agricultural manure spreaders, forage harvesters, silage conveyors and the like.
In the case of a towed machine like a forage harvester or spreader, the engine of the towing tractor provides motive power to move both the tractor and the towed machine along the ground. Such engine also delivers power to the "working" mechanism, e.g., the spreading mechanism, through what is known as a power take-off (PTO). Usually, the PTO is a rotating splined shaft or "power point" which projects rearward a short distance from the rear of the tractor frame.
The towed machine also has a variable-length PTO shaft which can be extended to connect to the tractor PTO. When so connected (and when the machine tongue is coupled to the tractor hitch bar), the machine is towed along the ground while its working mechanism performs the intended task. Another example of such a mobile machine, a manure spreader, is shown in U.S. Pat. No. 4,220,280 (Trott et al.).
A silage conveyor (for moving silage from a wagon into a silo) might be called a "quasi-mobile" machine in that it is moved only occasionally, e.g., from silo to silo. Such a conveyor need not be moving across the ground to perform its task. However, such quasi-mobile machines are often tractor-powered through a PTO shaft and can benefit from the invention.
Machinery of the foregoing types are not without problems. For example, the machine PTO shaft typically includes two drive components, e.g., male and female "telescoping" splined shafts, one of which is readily removable. The overall length of these shafts can be adjusted to connect to different makes and configuration of tractors.
However, when the towed machine and its PTO shaft are detached from the tractor and the machine put aside, the natural tendency of the PTO shaft is to hang angularly downward and, sometimes, touch the dirt. To prevent dirt contact and possible loss, the machine user removes a shaft component (the outward splined shaft, for example) and, often, stores it by simply tossing it into or onto the machine. Otherwise, such component (which can fall off of its own weight) may become lost or dirty.
Newer machines equipped with PTO shafts have a tube-like, non-rotating shield surrounding the shaft, spaced therefrom and mounted on shield support bearings. Like the PTO shaft, the shield also has two telescoping pieces to provide a variable overall length. The shield helps protect the PTO shaft and its universal joints from dirt, chaff and the like which cause premature wear. And like the outward splined shaft, the outward shield piece is readily removable.
A shield may be made of plastic or steel. When the machine is stored, the user often removes the outward PTO shaft assembly that includes the shield and PTO shaft and stores it. A machine equipped with an angularly-downward hanging PTO shaft and shield is shown in the aforementioned patent.
An improved machine having means to support the PTO shaft and shield away from dirt and which avoids having to remove and store shaft and shield components would be an important advance in the art.